When a plurality of like first connectors and like second connectors matable therewith are used in the same vicinity, it is important to provide means to permit mating of particular pairs intended to be mated to each other, while preventing mating of pairs not intended to be mated to each other. This may be accomplished by use of visual coding such as indicia, but is much preferred to be accomplished by keying mechanisms which physically prevent mating of connectors not intended to be mated to each other while allowing desired mating of appropriate pairs. In one manner of keying, key members are known which are secured in one of the first and second connectors which cooperate with opposing key members of the other. Each key member is secured in a selected orientation with respect to its opposing key member so that forward structure of both pass by each other during mating; if another like connector is used in place of one of them, with its key member oriented differently, the forward structure of the opposing key members will abut and prevent further axially forward movement and thereby prevent mating. Orientation of a key member in a connector can be accomplished by using a member of regular polygonal cross-section secured in a passageway of like cross-section, with the number of sides of the polygon determining the number of orientations available from which to select. Using a pair of key members increases the number of keying arrangements to equal the square of the number of sides of the polygon.
Polarizing first and second symmetrical or round connectors by another physical means such as using a polarizing key of one connector insertable into a corresponding channel of the other, will require the connectors to be placed in a proper angular orientation with respect to each other in order to begin mating engagement prior to key members having their forward structure meet each other. Polarization preserves the full number of keying arrangements in symmetrical connectors, instead of allowing mating of a first connector with one arrangement improperly with a second connector whose keys have an arrangement diametrically opposed to the one arrangement.
It is desired to provide polarization of a plurality of elongate plug connectors to be spaced side-by-side for mating to a corresponding single receptacle connector, in a manner which permits close spacing.
It is further desired to provide separate cavity sections in the receptacle connector with substantially narrow planar walls therebetween.
It is still further desired to provide a polarization means in the receptacle connector which does not require use of structure at ends of narrow plug-receiving cavities, so that the cavity ends can be utilized for means to align a narrow plug connector for insertion into a respective narrow cavity.